SH2-204 (Sharpless 204 ) Then nebula offers a lot for most setups but wider field of view systems will do best to capture most of the nebula. It responds very well to the hydrogen-alpha filter and poorly to standard color RGB filters. Creating an HA-RGB image is easier to create if you blend the H-Alpha with the RGB. The arc part of the nebula is bright but there is also a very faint area that picks up as well. For a complete list of the Sharpless Catalog visit my main site at http://www.sharplesscatalog.com